HIV Overview

What is a clinical trial?

A clinical trial is a research study in which people volunteer to help find answers to specific health questions. These studies are conducted according to a plan, called a protocol, which may include—

• New medicines or new combinations of medicines
• New medical devices or surgical procedures
• New, different ways to use an approved, existing medicine or device
• New ways to change behaviors to improve health

Clinical trials are conducted in several phases to determine whether new medical interventions are safe and effective in people. To get approval from the U.S. Food and Drug Administration (FDA), a new drug must go through three phases:

• Phase 1 Trial: Focuses on safety and dosage. A small group (typically 20–80 participants) receives the drug to determine safe dosage ranges and identify potential side effects.
• Phase 2 Trial: Evaluates effectiveness while continuing to monitor safety. Involves 100–300 participants with the condition being studied to determine how well the drug works and to make dosing changes if needed.
• Phase 3 Trial: Compares the new drug to existing treatments in a larger population (1,000–3,000 participants). Determines long-term effectiveness, safety, and side effects before seeking FDA approval.

Once a new drug is approved by the FDA, researchers often continue to track its safety in a Phase 4 Trial. This phase helps identify rare side effects, long-term outcomes, and how the drug performs in real-world settings.

What types of clinical trials are there?

The two main types of clinical trials are interventional trials and observational trials:

• An interventional study tests an intervention—a potential drug or treatment, medical device, or procedure—in people. Interventional studies are often designed in advance to directly evaluate the effects of new drugs or treatments on disease.
• An observational study does not directly test new treatments. Instead, researchers observe participants on an existing treatment plan and track health outcomes over time. Observational studies (also called epidemiologic studies) are mostly retrospective but can also follow participants over time.

What is an HIV and AIDS clinical trial?

HIV and AIDS clinical trials help researchers find better ways to prevent, detect, or treat HIV and AIDS. Every HIV medicine was first studied through a series of clinical trials.

Examples of HIV and AIDS clinical trials include—

• Studies of new medicines to prevent or treat HIV and AIDS
• Studies of vaccines to prevent or treat HIV
• Studies of medicines to treat infections related to HIV and AIDS, such as opportunistic infections

Can anyone participate in an HIV and AIDS clinical trial?

Participation in a clinical trial depends on the study. Some HIV and AIDS clinical trials enroll only people who have HIV, whereas other studies include people who do not have HIV.

Each HIV and AIDS clinical trial will also have specific criteria that can restrict who can participate in the study, including factors such as age, sex, pregnancy, HIV treatment history, or other medical conditions.

In addition, some clinical trials will only be available in a specific location. Even if someone meets the eligibility criteria, they may not be able to attend necessary visits to participate in the study.

What are the benefits of participating in an HIV and AIDS clinical trial?

Many people participate in HIV and AIDS clinical trials because they want to contribute to HIV and AIDS research. They may have HIV or know someone who has HIV.

People with HIV who participate in an HIV and AIDS clinical trial may benefit from new HIV medicines before they are widely available. For example, some ongoing clinical trials are studying long-acting HIV medicines that help reduce how often people with HIV have to take HIV medicines. See the HIVinfo Long-Acting HIV Medicine fact sheet for more information.

HIV medicines being studied in clinical trials are called investigational drugs. To learn more about investigational drugs, read the HIVinfo What is an Investigational HIV Drug? fact sheet or scan investigational HIV drugs using the Clinicalinfo Drug Database.

Another benefit of participating in an HIV and AIDS clinical trial is that participants can receive regular and careful medical care from a research team that includes doctors and other health professionals. Often, the medicines and medical care are free of charge during the study.

Sometimes people get paid for participating in a clinical trial. For example, they may receive money or a gift card. Participants may also be reimbursed for the cost of meals or transportation. 

Are HIV and AIDS clinical trials safe?

Researchers try to make HIV and AIDS clinical trials as safe as possible. However, volunteering to participate in a study testing an experimental HIV treatment can involve risks of varying degrees.

Most volunteers do not experience serious side effects; however, potential side effects that may be serious or even life-threatening can occur from the treatment being studied.

Before enrolling in a clinical trial, potential volunteers learn about the study in a process called informed consent. The process includes an explanation of the possible risks and benefits of participating in the study. Informed consent also covers how personal information will be shared during and after the study.

The FDA believes that obtaining a research participant's written informed consent is only part of the process. Once enrolled in a study, people continue to receive information about the study through the informed consent process. If a study intervention shows too much evidence of being dangerous, the study can also be terminated.

How can one find an HIV and AIDS clinical trial looking for volunteer participants?

There are several ways to find an HIV and AIDS clinical trial searching for volunteer participants:

• Use the “Find Studies” search feature on ClinicalTrials.gov to find HIV and AIDS studies looking for volunteer participants.
• Call an HIVinfo health information specialist at 1-800-448-0440 or email [email protected] to get support finding a clinical trial.
• Join ResearchMatch, which is a free, secure online tool that makes it easier for the public to become involved in clinical trials.

This fact sheet is based on information from the following sources:

From the National Institutes of Health (NIH):

• Are clinical studies for you?
• Clinical Trials: Information for Participants
• NIH Clinical Research Trials and You: The Basics

From the National Library of Medicine:

• Learn About Clinical Studies

Also see the HIV Source collection of HIV links and resources.